The overall goal of this research proposal is to define and biochemically characterize tissue specific and/or restricted histocompatibility antigens, and to evaluate their immunogenicity and significance in human renal, cardiac and liver allografts. By serological and cellular immune assays, we present evidence for such non-MHC antigenic systems in human kidney, heart and liver. Furthermore, the studies indicate that non-MHC antigens may play a role in the immunopathology of allograft rejection and development of coronary atherosclerosis in the cardiac allografts. We will continue characterization of non-MHC antigens using eluates prepared from rejected organs, allo- and heteroantisera and monoclonal antibodies. The specificities and cellular localization will be defined by immunofluorescence, immunoperoxidase and electron microscopy. To test the hypothesis that activated lymphocytes along with antibodies to B- lymphocytes and/or endothelial monocyte antigens (EM) play a role in the pathogenesis of coronary lesions, cellular assays will be developed. These will include primed lymphocyte typing (PLT) and cell-mediated lympholysis (CML) and the ability of MHC and non-MHC-specific antibodies to inhibit these reactions. Cultures of cloned biopsy-derived cells from recipients will also be tested for MHC and non-MHC antigen specificity using renal, cardiac, liver and endothelial tissues, normal fibroblasts and monouclear cells from blood as targets. We will continue the biochemical characterization of non-MHC EM antigens defined by the eluate, hetero- and alloantisera and the monoclonal antibodies using cell surface labeling, immunoprecipitation and characterization on SDS-PAGE. Relationships between antigens will be studied using sequential immunoprecipitation, two-dimensional gel electrophoresis and tryptic peptide mapping. cDNA probes for EM antigens will be isolated using two already available wavelengthgt11 expression vector cDNA libraries of antigen- positive human monocytic cell line (U937) and human umbilical vein endothelium. The results of these studies will define the relationship between serologically and cellularly defined non-MHC antigens, their biochemical nature and preliminary molecular genetics.